Clarification please: does the scene need to be free of existing intellectual properties, or can we do an homage/parody based on a franchise? Example: could I create and submit a scene of Batman watching over Gotham City?

The easiest way to check is to triangulate the mesh: hit CTRL+T while in editmode and the face count in the status bar will show the number of triangles. Be sure to undo or load the original file after doing this! 🙂